Google began to crackdown on the practice of purchasing of links to boost search results earlier this year, with even major brand names such as JC Penney being punished as a result.

Google began to crackdown on the practice of purchasing of links to boost search results earlier this year, with even major brand names such as JC Penney being punished as a result. Now, the search engine has sent out a wave of email notifications to webmasters who have bad links pointing to their websites.

Search Engine Land reports the messages inform website owners that poor-quality pages have linked to their domains and reminds them of Google's Webmaster Guidelines, which strictly prohibits the purchase and sale of links.

“Specifically, look for possibly artificial or unnatural links pointing to your site that could be intended to manipulate PageRank. Examples of unnatural linking could include buying links to pass PageRank or participating in link schemes,” the source quotes the email as saying. “We encourage you to make changes to your site so that it meets our quality guidelines.”

Earlier this year, the search engine launched a wave of email notifications to web owners for the opposite reason: Selling links to websites that lack credibility.

Google's objective is to penalize companies that practice black hat SEO or otherwise try to game its algorithm to bolster their rank. Brafton reported the search giant modified its algorithm with the Panda update, which favors sites that produce high-quality content and new iterations of this update continue to roll out.